1. Field of the Invention
The present invention relates to fasteners for attaching flexible cover sheets to rigid structures.
2. Prior Art
In the prior art, many different interlocking attachment devices have been utilized for anchoring a sheet of the material, such as canvas, vinyl, polethylene or the like to another structure. Normal uses of such sheets include boat covers, swimming pool covers, machinery covers, tent structures, truck box covers and similar usages.
Some of the types of interlocking attachment devices that have been advanced include a clamp member shown in U.S. Pat. No. 2,914,776 issued Dec. 1, 1959 to L. F. Hotz. This device is an edge clamp or retainer for a swimming pool cover. A separate resilient member on the lock channel is used for locking a cylindrical member in the edge portion of the sheet in place and the resilient member has to actually be deformed out of the way in order to effect the locking action.
An awning fastener is shown in U.S. Pat. No. 1,492,405 issued Apr. 29, 1924 to J. H. Stone. These fasteners are short clips that are used to hold a flexible sheet through the use of a relatively rigid stiffening rod along the edges of the awning. Another form of a swimming pool cover using a spring loaded clamp is shown in U.S. Pat. No. 2,815,809 issued Dec. 10, 1957 to E. L. Jacobs et al.
A retractable cover assembly and draw cord carrier for the cover is shown in the U.S. Pat. No. 3,051,232 issued Aug. 28, 1962 to J. H. Lamb. Other interlocking devices include the device shown in U.S. Pat. No. 3,373,464 issued Mar. 19, 1968 to S. Ausnit; and another device is shown in U.S. Pat. No. 2,247,846 issued July 1, 1941 to B. Perlman.
None of these structures, however, completely solve the problems of easy attachment and ease of release, and relatively inexpensive manufacturing costs both from a standpoint of the materials used and the cost of construction.